This 3 Degree Rear Arm Mount is CNC machined from 7075 aircraft grade aluminum and Anodized Black. This is offered as a single unit so you can purchase replacements if you break one of these, or as the complete kit (KHZKP390). These are designed to increase rigidity and add strength. M3 alloy set screws are added at the hinge pin holes to keep pins from wearing out the holes.